Komatsu PC200-8M0, Shop Manual, Page: 674 / 1254

302 Troubleshooting by failure code, Part 2
Failure code [CA2556] Grid Htr Relay Short Circuit Error
40-302
54
PC200, 200LC, 220, 220LC-8M0
SEN06134-00
Failure code [CA2556] Grid Htr Relay Short Circuit Error
Action
level
Failure code
Failure
Intake air Heater Relay Short Circuit
(Engine controller system)
L01 CA2556
Detail of failure q Short circuit is detected in drive circuit (primary circuit) of preheater relay.
Action of con-
troller
q
None in particular
Problem on
machine
q
Intake air heater does not work in auto preheating (degraded starting performance at low temper-
ature and emission of white smokes)
Related infor-
mation
q
Temperature sensed by boost temperature sensor can be checked with monitoring function.
(Code:
18500 )
q
Method of reproducing failure code: Turn starting switch to ON position (when boost temperature
is below -4 °C)
q
Troubleshooting for this failure code covers circuit starting from engine controller to primary (coil)
side of preheater relay R18.
q
For troubleshooting related to heater relay and secondary side of preheater relay R18, see E-2 in
E-mode.
Cause Procedure, measuring location, criteria and remarks
1
Defective wiring harness connec-
tor
See descriptions of wiring harness and connectors in "c: Electrical equipment"
in "Checks before troubleshooting" of "General information on troubleshoot-
ing", and check them.
2 Defective preheater relay R18
1. Turn starting switch to OFF position.
2. Disconnect relay R18, and connect T-adapters to male side.
Between R18 (male) (1) and (2) Resistance
200 to
400
z
1. Turn starting switch to OFF position.
2. Replace relay R18 with another one.
3. Turn starting switch to ON position.
If this failure code disappears, original preheater relay R18 is defective.
3 Ground fault in wiring harness
1. Turn starting switch to OFF position.
2. Disconnect connector CE02 and relay R18, and connect T-adapters to
either female side.
Between CE02 (female) (40) or R18 (female) (1)
and ground
Resistance Min. 1 M
z
4 Short circuit in wiring harness
1. Turn starting switch to OFF position.
2. Disconnect connector CE02 and relay R18, and connect T-adapters to
female side of CE02.
a
Check with multimeter in continuity mode.
Between CE02 (female) (40) and each pin other
than (40) No continuity
(No sound is heard)
5 Defective engine controller
If no failure is found by above checks, engine controller is defective. (Since
this is an internal defect, troubleshooting cannot be performed.)